Abstract: The invention is directed to a digital phase detector that comprises a splitter and phase shifter to receive a signal of a device under test and produce a first signal that is substantially identical to the received signal and a second signal that is phase shifted relative to the first signal. A first analog-to-digital channel processes the first signal to produce an in-phase and quadrature signals. The second signal is processed by a second analog-to-digital channel to produce a second set of in-phase and quadrature signals. The two sets of in-phase and quadrature signals are used to determine a phase difference between the signal of the device under test and a local oscillator signal associated with the two analog-to-digital channels. The invention is further directed to a direct digital synthesizer that is capable of use within the digital phase detector and in other applications.

Abstract: The invention is directed to a digital phase detector that comprises a splitter and phase shifter to receive a signal of a device under test and produce a first signal that is substantially identical to the received signal and a second signal that is phase shifted relative to the first signal. A first analog-to-digital channel processes the first signal to produce an in-phase and quadrature signals. The second signal is processed by a second analog-to-digital channel to produce a second set of in-phase and quadrature signals. The two sets of in-phase and quadrature signals are used to determine a phase difference between the signal of the device under test and a local oscillator signal associated with the two analog-to-digital channels. The invention is further directed to a direct digital synthesizer that is capable of use within the digital phase detector and in other applications.

Abstract: An improved system for providing ensemble time from an ensemble of oscillators is provided. The improved system provides an ensemble time definition whose large number of possible solutions for an ensemble time are constrained to a limited number of solutions. In one embodiment, a substantially infinite number of solutions is constrained to a single solution.

Abstract: An improved system for providing ensemble time from an ensemble of oscillators is provided. In the system, a more complete ensemble definition permits a more accurate ensemble time to be calculated. The system takes into account at least weighted time and weighted frequency aspects or weighted time and weighted frequency aging aspects of each oscillator in the ensemble. Preferably, the system takes into account all of the weighted time aspects, weighted frequency aspect, and weighted frequency aging aspects for each oscillator in the ensemble. The weights with respect to each clock can be chosen to be either zero or any positive value such that the sum of the weights for each aspect sum to one. The system can be implemented using a Kalman approach.